Dance dialects and foraging range in three Asian honey bee species

Summary We measured the distance dialects in the dance languages of three honey bee species in Thailand (Apis florea, A. cerana, and A. dorsata), and used these dialects to examine the hypothesis that a colony's dialect is adaptively tuned to enhance efficiency of communication over the distances that its foragers typically fly. in contrast to previous interspecific comparisons in Sri Lanka (Lindauer 1956; Punchihewa et al. 1985), we found no striking dialect differences among the Asian bees in Thailand. The adaptive tuning hypothesis predicts that the foraging ranges of the three species should also be similar, but comparisons of colonial foraging range using the forage mapping technique (Visscher and Seeley 1982) actually revealed marked differences. This raises the possibility that the link between ecology and distance code is more subtle than previously supposed, if a link exists at all. Offprint requests to: F.C. Dyer     

Climate change and the cost of conserving species in Madagascar

We examined the cost of conserving species as climate changes. We used a Maxent species distribution model to predict the ranges from 2000 to 2080 of 74 plant species endemic to the forests of Madagascar under 3 climate scenarios. We set a conservation target of achieving 10,000 ha of forest cover for each species and calculated the cost of achieving this target under each scenario. We interviewed managers of projects to restore native forests and conducted a literature review to obtain the net present cost per hectare of management actions to maintain or establish forest cover. For each species, we added hectares of land from lowest to highest cost per additional year of forest cover until the conservation target was achieved throughout the time period. Climate change was predicted to reduce the size of species' ranges, the overlap between species' ranges and existing or planned protected areas, and the overlap between species' ranges and existing forest. As a result, climate change increased the cost of achieving the conservation target by necessitating successively more costly management actions: additional management within existing protected areas (US$0-60/ha); avoidance of forest degradation (i.e., loss of biomass) in community-managed areas ($160-576/ha); avoidance of deforestation in unprotected areas ($252-1069/ha); and establishment of forest on nonforested land within protected areas ($802-2710/ha), in community-managed areas ($962-3226/ha), and in unprotected areas ($1054-3719/ha). Our results suggest that although forest restoration may be required for the conservation of some species as climate changes, it is more cost-effective to maintain existing forest wherever possible.     

Estimating species richness and accumulation by modeling species occurrence and detectability

A statistical model is developed for estimating species richness and accumulation by formulating these community-level attributes as functions of model-based estimators of species occurrence while accounting for imperfect detection of individual species. The model requires a sampling protocol wherein repeated observations are made at a collection of sample locations selected to be representative of the community. This temporal replication provides the data needed to resolve the ambiguity between species absence and nondetection when species are unobserved at sample locations. Estimates of species richness and accumulation are computed for two communities, an avian community and a butterfly community. Our model-based estimates suggest that detection failures in many bird species were attributed to low rates of occurrence, as opposed to simply low rates of detection. We estimate that the avian community contains a substantial number of uncommon species and that species richness greatly exceeds the number of species actually observed in the sample. In fact, predictions of species accumulation suggest that even doubling the number of sample locations would not have revealed all of the species in the community. In contrast, our analysis of the butterfly community suggests that many species are relatively common and that the estimated richness of species in the community is nearly equal to the number of species actually detected in the sample. Our predictions of species accumulation suggest that the number of sample locations actually used in the butterfly survey could have been cut in half and the asymptotic richness of species still would have been attained. Our approach of developing occurrence-based summaries of communities while allowing for imperfect detection of species is broadly applicable and should prove useful in the design and analysis of surveys of biodiversity.     

External and internal carbonic anhydrases in Dunaliella species

Four species of Dunaliella and a carbonic anhydrase deficient mutant of Dunaliella tertiolecta (Butcher), HL 25/8, developed a process for concentrating dissolved inorganic carbon when adapted on air or low CO₂ for 24 h in the light. However, the external carbonic anhydrase activities in Dunaliella species were nil or low compared with those in Chlamydomonas reinhardtii (Danegard) or some Chlorella species. D. tertiolecta had low and about equal levels of external and internal carbonic anhydrase. D. parva (Lerche) and the D. tertiolecta mutant had negligible external carbonic anhydrase. D. viridis (Teodoresco) and D. salina (Teodoresco), high salt tolerant species, had high activities of intenal carbonic anhydrase but low levels of external carbonic anhydrase. Antiserum prepared against the 37 kDa peptide of extracellular carbonic anhydrase from Chlamydomonas reinhardtii was immunoreactive with a polypeptide of 30 kDa in D. tertiolecta and its salt sensitive external carbonic anhydrase (CA) mutant HL 25/8. External CA activity from D. tertiolecta was stimulated about three-fold, by including 0.5 M NaCl in the assay medium, while internal CA was not significantly affected by NaCl. External CA activities in the other species were insensitive to NaCl, while their internal activities were 90% inhibited by 0.5 M NaCl. Sorbitol only partly replaced NaCl in stimulating the external CA from D. tertiolecta. These experiments were performed with Dunaliella spp. grown in controlled laboratory cultures during September through November 1989.     

Spatial and temporal distribution of atmospheric mercury species over the Adriatic Sea

Field measurements of atmospheric mercury and related species were carried out during an intensive cruise campaign performed over the Adriatic sea from October 26th to November 12th, 2004 on board the R/V Urania. Hg⁰ ranged between 0.8 and 3.3 ng/m³ with an average of 1.6 ± 0.4 ng/m³ over the entire period. Hg(II) concentrations ranged from 0.1 to 62.8 pg/m³ with an average of 6.7 ± 11.7 pg/m³ whereas Hg-p levels were in a range of 0.04 and 51 pg/m³ with an average of 4.5 ± 8 pg/m³. Higher Hg⁰ and Hg-p concentrations were observed in the Gulf of Venice and Gulf of Trieste due primarily to air masses transported from the mainland reflecting the contribution from anthropogenic sources. In contrast, higher Hg(II) concentrations observed during the first period of the cruise campaign were likely due to the occurrence of photo-oxidants production which are the main players of the gas phase oxidation of to Hg(II)_(g). These findings have been confirmed by the backward trajectories analysis of air masses crossing the studied area during selected days.     

Accuracy of species and abundance minimal areas determined by similarity area curves

A new method for estimating the accuracy of a representative ecological sample (species minimal area and abundance minimal area determined by similarity area curves) is presented. Formulas are derived to calculate the adequate similarity level (I_S, respectively I_K) in relation to the desired accuracy of the sample: I_S=2 w/1+w for qualitative similarity and _K=2 x/(1+x)(1+y) for quantitative similarity, where w=desired qualitative accuracy of the sample, x=desired quantitative accuracy of the sample, y=abundance proportion of rare species. Based on samples from a low diversity environment in the supralittoral fringe of rocky shores (black zone), the new approach was tested and led to the following results: (1) Similarity area curves are an objective method to calculate the minimal area and to test the accuracy of the sample size chosen. (2) A large presample is necessary to calculate the minimal area. (3) The size of minimal area is subject to seasonal and regional variations. (4) Incidental species lead to an overestimation of the species minimal area. (5) Highly dominant species lead to an underestimation of the abundance minimal area.     

Uptake and elimination kinetics of triphenyltin hydroxide by two fish species

The uptake from water and the elimination of carbon‐14 radiolabelled triphenyltin hydroxide ([¹⁴C]TPTH) was studied in two fish species: guppy (Poecilia reticulata) and rainbow trout larvae (Salmo gairdneri). During all the experiments no steady state in fish was found. TPTH was rapidly taken up, while elimination was very slow. Uptake and elimination rate constants (k ₁ and k ₂, respectively), and a bioconcentration factor were estimated, assuming first order kinetics.

During eight days of exposure of guppy to TPTH an uptake rate constant k ₁ of 70±7L/kg.d and an elimination rate constant k ₂ of 0.005 ±0.029d ^‐1 was found. This resulted in a biconcentration factor of at least 2.1 × 10³L/kg (wet weight). Comparable results were obtained during a 30 days exposure experiment with guppy: k ₁ was 41±2L/kg.d, k ₂ 0.014 + 0.002d^‐1, and the bioconcentration factor was estimated to be 2.9 × 10³ L/kg (wet weight).

Four days exposure of rainbow trout larvae resulted in a it, of 22+ 2 L/kg.d, and a k ₂ of 0.031 ±0.007d^‐1. Using these k, and k ₂ values it was estimated that the biconcentration factor exceeds 650 L/kg (wet weight).     

Effects of salinity on respiration and nitrogen excretion in two species of echinoderms

The 30-d survival limit of Eupentacta quinquesemita and Strongylocentrotus droebachiensis is 12–13 S. The activity coefficient (1 000/righting time in seconds) of stepwise acclimated sea urchins declined from 16.3 at 30 S to 3.5 at 15 S. Oxygen consumption rates (QO₂) of both species held at 30 S and 13°C were highest in June and lowest in December. During the summer, when environmental salinity is most variable in southeastern Alaska, the QO₂ of both species held at 30, 20 and 15 S varied directly with salinity. Perivisceral fluid PO₂ varied directly with acclimation salinity in sea urchins, but not in sea cucumbers. Perivisceral fluid oxygen content of acclimated sea urchins was significantly lower at 15 and 20 S than at 30 S due to reduced PO₂ and extracellular fluid volume at the lower salinities. The QO₂ of both species varied directly with ambient salinity during a 30-10-30. semidiurnal pattern of fluctuating salinity. No change occurred in the average QO₂ of either species over a 15-30-15. semidiurnal pattern of fluctuating salinity. Sea urchin perivisceral fluid PO₂ declined as ambient salinity fluctuated away from the acclimation salinity in both cycles and increased as ambient salinity returned to the acclimation salinity. Total nitrogen excretion of stepwise acclimated sea cucumbers declined significantly from 30 to 15 S, but there was no salinity effect on total nitrogen excretion in sea urchins. Ammonia excretion varied directly with salinity in stepwise acclimated sea cucumbers (67–96% of total nitrogen excreted), but there was no salinity effect on ammonia excretion (89–95% of total nitrogen excreted) of sea urchins. Urea excretion did not vary with salinity in sea cucumbers (2–4% of total nitrogen excreted) or sea urchins (2–9% of total nitrogen excreted). Primary amines varied inversely with salinity in sea cucumbers (2–30% of total nitrogen excreted), but did not vary with salinity in sea urchins (2–4% of total nitrogen excreted). The oxygen: nitrogen ratio of both species indicated that carbohydrate and/or lipid form the primary catabolic substrate. The O:N ratio did not vary as a function of salinity. Both species are more tolerant to reduced salinity than previously reported, however, rates of oxygen consumption and/or nitrogen excretion are modified by salinity as well as season.     

Spatial heterogeneity influences native and nonnative plant species richness

Spatial heterogeneity may have differential effects on the distribution of native and nonnative plant species richness. We examined the effects of spatial heterogeneity on native and nonnative plant species richness distributions in the central part of Rocky Mountain National Park, Colorado, USA. Spatial heterogeneity around vegetation plots was characterized using landscape metrics, environmental/topographic variables (slope, aspect, elevation, and distance from stream or river), and soil variables (nitrogen, clay, and sand). The landscape metrics represented five components of landscape heterogeneity and were measured at four spatial extents (within varying radii of 120, 240, 480, and 960 m) using the FRAGSTATS landscape pattern analysis program. Akaike's Information Criterion adjusted for small sample size (AICc) was used to select the best models from a set of multiple linear regression models developed for native and nonnative plant species richness at four spatial extents and three levels of ecological hierarchy (i.e., landscape, land cover, and community). Both native and nonnative plant species richness were positively correlated with edge density, Simpson's diversity index and interspersion/juxtaposition index, and were negatively correlated with mean patch size. The amount of variation explained at four spatial extents and three hierarchical levels ranged from 30% to 70%. At the landscape level, the best models explained 43% of the variation in native plant species richness and 70% of the variation in nonnative plant species richness (240-m extent). In general, the amount of variation explained was always higher for nonnative plant species richness, and the inclusion of landscape metrics always significantly improved the models. The best models explained 66% of the variation in nonnative plant species richness for both the conifer land cover type and lodgepole pine community. The relative influence of the components of spatial heterogeneity differed for native and nonnative plant species richness and varied with the spatial extent of analysis and levels of ecological hierarchy. The study offers an approach to quantify spatial heterogeneity to improve models of plant biodiversity. The results demonstrate that ecologists must recognize the importance of spatial heterogeneity in managing native and nonnative plant species.     

Cryptic species and population structuring of the Atlantic and Pacific seabob shrimp species, Xiphopenaeus kroyeri and Xiphopenaeus riveti

Seabob shrimps of the genus Xiphopenaeus are important fishery resources along the Atlantic and Pacific coasts of Central and South America. The genus was considered to comprise two species: the Atlantic Xiphopenaeus kroyeri (Heller, Sitzungsber Math Naturwiss cl kaiserliche Akad Wiss Wien 45:389–426, 1862), and the Pacific Xiphopenaeus riveti (Bouvier, Bull Mus Hist Nat Paris 13:113–116, 1907). In a recent review, Xiphopenaeus was regarded as a monotypic genus, on the basis that no clear morphological differences could be found between Pacific and Atlantic specimens (Pérez Farfante and Kensley, Mem Mus Nat Hist Nat Paris 175:1–79, 1997). In the present work, nuclear (allozymes), and mitochondrial (Cytochrome Oxidase I) genes were used to demonstrate the validity of X. riveti and reveal the presence of two cryptic species of Xiphopenaeus within X. kroyeri in the Atlantic Ocean. The high levels of molecular divergence among these species contrast with their high morphological resemblance. Interspecific sequence divergences (Kimura 2-parameter distance) varied from 0.106 to 0.151, whereas intraspecific distances ranged from 0 to 0.008 in Xiphopenaeus sp. 1, from 0 to 0.003 in Xiphopenaeus sp. 2, and from 0.002 to 0.005 in X. riveti. In addition, five diagnostic allozyme loci were found between sympatric samples of Xiphopenaeus sp. 1 and 2 along the Brazilian coast. The results suggest that Xiphopenaeus sp. 2 from the Atlantic is more closely related to the Pacific X. riveti than to the Atlantic Xiphopenaeus sp. 1. Furthermore, a high level of genetic structuring (Xiphopenaeus sp. 1: F _ST =0.026; P<0.05; Xiphopenaeus sp. 2: F _ST =0.055; P<0.01) was found in the Brazilian Xiphopenaeus populations, indicating the presence of different genetic stocks in both Atlantic species. These findings have important commercial implications as they show that the fisheries of the two Atlantic species must be managed separately, and that each one is comprised of different populations.Communicated by O. Kinne, Oldendorf/Luhe     

Mating success of male hermit crabs in shell generalist and shell specialist species

Summary The reproductive behavior of two species of diogenid hermit crabs was studied in Hawaii. In the shell generalist, Clibanarius zebra, male reproductive success varied little with size, although the largest males were less successful in obtaining copulations than were medium-large males. Male and female size were positively correlated, in successful pairs, thus larger males had the potential to fertilize more eggs when they were successful in obtaining a copulation. Female fecundity in C. zebra was not affected by species of gastropod shell inhabited once female size was taken into account. Male copulatory success was very strongly influenced by the species of gastropod shell inhabited. Males in Trochus or Nerita shells had greatly reduced reproductive success compared to males in Turbo or Nassarius shells. This result was due both to (1) males in Trochus especially dropping and otherwise poorly handling females during precopulatory behavior and (2) females not responding to precopulatory behavior patterns executed by males in Trochus and Nerita. Transferring males from good to bad shapes of shells and vice versa showed that male success was a function of shell type inhabited and not some correlated feature of the crabs. In the shell specialist, Calcinus seurati, which is found primarily in Nerita shells as an adult, males in Nerita shells were quite successful in obtaining copulations.     

Sodium and potassium in the edible portions of thirty fish species

The 30 species of limnic and marine fishes analyzed in the present study represent excellent foods for inclusion in diets that require a low sodium content. In none of these species, not even in the marine ones, did the content of sodium exceed the maximum amount (100 mg/100 g fish meat) specified by food authorities for low sodium diets.     

Differences in olfactory species recognition in the females of two Australian songbird species

Although birds have recently been shown to possess olfactory abilities and to use chemical cues in communication, limited effort has been made to demonstrate the use of odorants in social contexts. Even less is known regarding the use of odorants in species recognition. The ability to recognize conspecifics should be more pronounced in social species. This study investigated the importance of olfactory cues in species recognition in females of two estrildid finch species with different levels of sociality. Combining odor preference tests with chemical analyses, we surveyed whether female zebra finches and diamond firetails are able to distinguish between the species based on volatile traits and whether individuals exhibit species-specific differences in body odorants. Zebra finches are more social than diamond firetails; nevertheless, both species have an overlapping distribution area. Applying an experimental Y-maze paradigm, we showed that zebra finches can use differences in their species odor fingerprints and displayed a significant preference for the odor of conspecifics over that of heterospecifics, whereas diamond firetails did not reveal a preference. Using gas chromatography and mass spectrometry, we demonstrated that body odorants of the two species were significantly different in relative composition. This finding demonstrates the potential importance of olfactory cues in species recognition, at least in social bird species. Even these two closely related species displayed remarkable differences in their responsiveness to similar chemical cues, which might be caused by species-specific differences in ecology, physiology, or evolution.     

Sediment-rejection efficiency of 22 species of Australian scleractinian corals

Sediment-rejection rates of 22 Australian midshelf coral species were studied in situ between March and July 1988 at Lizard Island, Great Barrier Reef. Rejection rates of non-branching species were positively correlated with calice size and were faster for fine (63 to 250 m) than for coarse (500 to 1000 m) sediment at influxes of 200 mg/cm². Increasing water turbulence was a more important influence on rejection rates for some species than for others. Most replicates of most species cleared all sediment in 2 d. Of those that did not, some Favia stelligera and Leptoria phrygia showed partial tissue death within 48 h, and Gardineroseris planulata showed partial tissue death within 6 d. Montipora aequituberculata, Porites lobata and P. lutea tolerated sediment for at least 6 d, and exhibited extensive tissue bleaching, but these tissues recovered after sediment removal. Sediment-rejection efficiency and sediment tolerance are not directly related, and wide interspecific differences may occur in both. These findings are correlated with differences in sediment-rejection mechanisms and with ecological distributions on the reef.     

The importance of considering multiple interacting species for conservation of species at risk

Conservation of species at risk of extinction is complex and multifaceted. However, mitigation strategies are typically narrow in scope, an artifact of conservation research that is often limited to a single species or stressor. Knowledge of an entire community of strongly interacting species would greatly enhance the comprehensiveness and effectiveness of conservation decisions. We investigated how camera trapping and spatial count models, an extension of spatial-recapture models for unmarked populations, can accomplish this through a case study of threatened boreal woodland caribou (Rangifer tarandus caribou). Population declines in caribou are precipitous and well documented, but recovery strategies focus heavily on control of wolves (Canis lupus) and pay less attention to other known predators and apparent competitors. Obtaining necessary data on multispecies densities has been difficult. We used spatial count models to concurrently estimate densities of caribou, their predators (wolf, black bear [Ursus americanus], and coyote [Canis latrans]), and alternative prey (moose [Alces alces] and white-tailed deer [Odocoileus virginianus]) from a camera-trap array in a highly disturbed landscape within northern Alberta's Oil Sands Region. Median densities were 0.22 caribous (95% Bayesian credible interval [BCI] = 0.08–0.65), 0.77 wolves (95% BCI = 0.26–2.67), 2.39 moose (95% BCI = 0.56–7.00), 2.64 coyotes (95% BCI = 0.45–6.68), and 3.63 black bears (95% BCI = 1.25–8.52) per 100 km². (The white-tailed deer model did not converge.) Although wolf densities were higher than densities recommended for caribou conservation, we suggest the markedly higher black bear and coyote densities may be of greater concern, especially if government wolf control further releases these species. Caribou conservation with a singular focus on wolf control may leave caribou vulnerable to other predators. We recommend a broader focus on the interacting species within a community when conserving species.     

Scaling toxicity data across species

The response of various species to doses of chemicals can often give the impression that some (such as cattle in the case of molybdenum) are much more susceptible than others to these chemicals. These impressions usually rely on an underlying assumption that equivalent doses are based on mg of the chemical per kg body weight of the animal. That is, that doses scale as the first power of body weight. This assumption is more often wrong than right. When viewed in a more general way, where the scaling is proportional to a power of the body weight and the exponent determined empirically, it is often found that equivalent doses scale with an exponent in the range of 0.6 to 0.8. As a result, larger animals are indeed more susceptible to toxicity on a mg kg^–1 body weight basis, but this is not because of unique differences in the species, but only because of different body sizes. This method of scaling is called allometry or allometric scaling. An early version of this approach was based on body surface area where the exponent is 2/3. More recently, pharmacokinetics has revealed that the reason for the different response of larger animals is related to the slower metabolic and clearance rates for larger animals which give rise to larger biological half-lives for chemicals in the body and to higher tissue concentrations per given dose.     

Ingestion and assimilation of nitrogen from benthic sediments by three species of coral

We quantified the nitrogen and enzyme hydrolyzable amino acid (EHAA) concentrations of sediments prior to and after corals sloughed, ingested, and egested sediments layered onto their surfaces, for the three coral species Siderastrea siderea, Agaricia agaricites, and Porites astreoides in Jamaica. The percent nitrogen of the sediments egested by all three species was lower than in the sediments available to the corals. Additionally, the sediments sloughed (not ingested) by A. agaricites and P. astreoides were lower in percent nitrogen, while the sediments sloughed by S. siderea had the same percent nitrogen as that of the available sediments. The percent nitrogen of the sediments sloughed and egested by P. astreoides showed significant negative and positive relationships, respectively, to increasing sediment loads, while the percent nitrogen of the sediments sloughed and egested by both S. siderea and A. agaricites showed no relationship to sediment load. EHAA concentrations were not significantly different between the sloughed and available sediments but were significantly lower in the sediments egested by S. siderea and A. agaricites (EHAA concentrations were not measured for P. astreodies sediment fractions). Comparisons of the nitrogen and EHAA concentrations in the sloughed and egested sediments to what was available prior to coral processing show that maximum ingestion was between 0.1 and 0.2 µg N µg^–1 coral N cm^–2 and between 0.5 and 0.6 µg EHAA·cm^–2. Maximum assimilation efficiencies were estimated to be 30–60% of the available nitrogen. The data show that corals ingest and alter the nitrogen concentration of particles that land on their surfaces. The corals abilities to process these sediments, and the sediments possible contributions to coral nutrition, are discussed based on these results.Communicated by O. Kinne, Oldendorf/Luhe     

Reproductive effort in four species of intertidal limpets

Reproductive effort was measured in 4 species of intertidal limpets: Cellana tramoserica (Sowerby) Notoacmea petterdi (Tenison Woods), Patella peroni Blainville and Patelloida alticostata (Angas) from south-eastern Australia. Field studies between 1971 and 1975 enabled indices of reproductive effort to be obtained using both gonad to body weight ratios and energy budgets. The ratio of annual gonad production to somatic tissue energy content is highest for Patella peroni (2.19). The ratios for C. tramoserica and Patelloida alticostata are lower but similar (1.02), and N. petterdi has the lowest ratio (0.78). The percentage of assimilated energy allocated to reproduction is also highest in Patella peroni (26.6%), but this index of reproductive effort is similar for the other three species (10.3 to 12.9%). Consequently, these 4 species are ranked in different orders with respect to reproductive effort, depending upon which index is used. However, the difference between both indices is small, and is less than has usually been anticipated. The difference is interpreted as being the result of the low metabolic rate of N. petterdi rather than as evidence for the inadequacy of one of the indices of reproductive effort.     

Illumination and the coral community beneath tabular Acropora species

Light profiles beneath the tabular coral species Acropora cytherea and A. hyacinthus were examined at Rib and Broadhurst Reefs, central Great Barrier Reef, in November 1980. They show a strongly decreasing illumination gradient towards the central stem. Beneath tables at 10m deep, which receive about 7.0 mW cm^–2 at solar noon, substrate irradiance falls to a minimum of about 5% ambient or to about 0.4 mW cm^–2. Thus, from previously reported compensation values, most sub-table substrate may receive above-compensation irradiance. Illumination beneath tables screened by foil is significantly lower. The coral communities beneath tables of these two species plus those of A. subulata and A. clathrata support an average 26 colonies m^–2, at a cover of 40%, nearly identical to adjacent, unshaded quadrats. Species richness is likewise very similar. Species richness and colony density beneath the tables increase inwards from the perimeter of the shaded areas, decreasing only near the central stems. Dark adaptation and reduced competitive and grazing pressure are suggested explanations for the latter. It is concluded that shading does not provide a significant competitive advantage for Acropora spp. tables at 10 m deep.